1. Field of the Invention
The invention is related to the field of heat sinks, and in particular, to a modular heat sink assembly that has a larger main heat sink member with one or more smaller additional heat sink members that are assembled within voids in the main heat sink member in a movable fashion. The additional heat sink members are thermally connected to the main heat sink member, such as through heat pipes, but are able to move within the voids in the main heat sink member to accommodate different component heights on circuit boards.
2. Statement of the Problem
Computers, routers, and other electronic devices are built with processors, memory, and other electronic components that are fabricated on circuit boards. Each of the active components on the circuit board draws a current in order to operate. When a component draws a current, thermal energy (or heat) is created in the component. If the thermal energy in the component increases above a maximum threshold level, then the component may be damaged. One way to protect the component is to use a heat sink to remove heat from electronic components.
A heat sink is a device that absorbs and dissipates heat from a component which is in thermal contact with the heat sink. A heat sink functions to efficiently transfer thermal energy from the component to the heat sink, which has a much greater surface area and heat removal capacity. A typical heat sink is formed from a metal, such as copper or aluminum, which has a high thermal conductivity. One surface of the heat sink includes a plurality of fins which creates a large surface area for dissipating heat. When the thermal energy is transferred from the component to the heat sink, the thermal energy is rapidly dissipated to the surrounding environment due to the large surface area of the fins, which cools the component.
Circuit boards may include multiple components that have a high enough thermal energy, and consequently a higher temperature, that heat sinks are needed or desired. For example, microprocessors, power-handling semiconductors, Application-Specific Integrated Circuits (ASIC), etc, typically draw higher currents than other components, and consequently operate at a higher temperature. To provide the desired heat dissipation for the components on the circuit board, an individual heat sink is typically mounted on each of the components on the circuit board. The size of an individual heat sink may depend on the heat dissipation needs for a given component.
As the size of circuit boards decreases to accommodate smaller electronic devices, there is much less room for individual heat sinks. If two or more components are mounted on a circuit board next to each other, there may not be room to mount an individual heat sink on each of the components. This may result in damage to one or more of the components if the heat generated during operation exceeds a maximum rated temperature for the component.
One solution to the problem of individual heat sinks is to use one or more larger heat sinks. A large heat sink is simultaneously mounted on multiple components in order to dissipate the heat from the components. Unfortunately, there can also be problems associated with a large heat sink. For one, a large heat sink may conduct excessive thermal energy from one component to another, creating the potential for thermal damage. Also, the components on the circuit board may have varying heights in relation to the top of the circuit board, which makes using a large heat sink difficult to use. The large heat sink can also apply excessive or uneven force to the components with the greater heights, which can damage the components.
This can especially be a problem when the covers or lids on a component are removed or are omitted during fabrication. Lids are formed on components to protect the fragile components from damage. The lid of a component, commonly formed from aluminum or plastic, may have thermal impedance that negatively affects the dissipation of the heat from the active component underneath the lid. Thus, the lids are sometimes removed, or are omitted during fabrication, so that the heat sink can directly contact the active element instead of contacting the lid. However, when the lid is removed, the component is very susceptible to damage. If a large heat sink is used on a circuit board having one or more lid-less components, then the force applied by the large heat sink can damage the components.